Radio pulse transmitter with rotating antenna



April 2 2 J. K. MCKENDRY RADIO PULSE TRANSMITTER WITH ROTATING ANTENNA Filed Feb. 19, 1945 R E5 M, Q 0 mM m 269: $1 K (M @m 35am 8% N 55% w N J mwt YE Y B Q 7 s @E as 5K QE SEQ #3 QB XGSRS: 658mg QE $55 53% G Q2086 fiif $686 $1 wmoaomsiw .396 P .393 Q .398 gm wmww Patented Apr. 29, 1952 RADIO PULSE TRANSMITTER WITH ROTATING ANTENNA John K'. McKendry, Cambridge, Mass., assignor,

by mesne assignments, to the United States of America as represented by the Secretary of War Application February 19, 1945, Serial No. 578,770

3 Claims. (c1. 250-17) This invention relates to electrical systems and more particularly to electrical systems for con-' trolling electrical driving means.

In some radio applications, use is made of 'aradiating element rotated about the axis of a parabolic reflector to produce a beam of energy.

that describes a conical path in space. The rotation of this radiating element is usually accomplished by means of a drive motor or, to use a term common to the art, spinner motor." -In some applications the energy is not radiated continuousIy' but may be radiated in pulses, such pulses of energy usually recurring at predetermined fined intervals of time. In some applications it"is' advantageous to havethe number of. pulses radiated per revolution of the antenna element remain constant.

One object of this invention, therefore, is to provide an electrical system for synchronizing the I rotation of a radiating element with pulses fedto this radiating element from a transmitter so that the number of pulses transmitted per revolution will be constant.

Another object of the invention is to provide an electrical jsystem for controlling an electrical drivingmeans.

In accordance with the present invention there is; provided an electrical system for moving an electrical driving means at a predetermined speed. 'fI 'his system comprises a source of reference voltage and an electrical drivin means. A proportionmg means is also included in this system for subdividing the reference voltage and applying it to the driving means. This propor tioning'me'ans also serves to furnish the energy to the driving means.

Where'the driving means is adapted to move a radiating means and the reference voltage is used to synchronize a transmitter which feeds the radiating means it is readily seen that such a system serves to synchronize the movement of the radiating means whereby the number of pulses transmitted per cycle of movement of the radiating means is constant. I

For a better understanding of the invention together with other and further objects thereof, reference is made to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

The accompanying drawing shows the invention in block diagram form.

Referring now to the drawing, the block diagram shown represents one embodiment of the invention. In this drawing and the explanation connected with it reference is made to specifi frequencies, specific circuits and specific division ratios. It is to be understood that thesereferences are made for ease of explanation only and are not intended nor should they be so construed as to limit the invention to the frequencies, circuits, or frequency divisions mentioned.

A multivibrator 5 is synchronized by a reference voltage of 800 cycles per second so that it operates at a frequency of 200 cycles per second or that of the reference voltage. A portion of the output of this multivibrator 5 is fed to a second multivibrator 16 to synchronize it at a frequency of 50 cycles per second, or no: the input frequency or 1% that of the reference frequency.- The multivibrators used in this example could be replaced by any of the circuits well known to the art that will perform the required'frequency division,

The output of the multivibrator' 6 is fed through a 50 cycle filter I. A-Wien bridge filter is shown in the block as an example of a type of filter that will perform satisfactorily. The output of the fllter is fed to an inverter circuit 8 as a control voltage. An example of an inverter circuit that may be used is described in connection with Fig. 170, page 265 of Engineering Electronics by Donald G. Fink, First Edition, published by McGraw- Hill Book Company, Inc. It is possible to replace the inverter circuit witha power amplifier or any other means well known to the art that will provide sufiicient power to drive the spinner motor and may be synchronized by the subdivided reference frequency. The output of the inverter is applied to an electrical driving means 9, preferably a synchronous motor as shown. The shaft of this motor is mechanically coupled to a radiating element It]. A gear train i I is shown between the spinner motor 9 and the radiatin element 10. The purpose of the gear train is to cause the radiating element to rotate at a speed different from that of the spinner motor 9. The inclusion of the gear train I i is not essential to the successful operation of the invention and may be omitted in many applications.

The same 800 cycle reference voltage that was fed to multivibrator 5 is also fed to the transmitter Has a synchronizing voltage. The output of the transmitter I4 is a series of radio frequency energy pulses occurring in a definite predetermined time relationship with the input synchronizing voltage; The number of pulses occurring per second is known as the pulse repetition frequency. In this example it has been assumed that one pulse is sent out from the transmitter for each cycle of input reference subdivided reference frequency is supplied by inverter 8 to spinner motor 9, and, therefore, drives this motor at a speed determined by the frequency of the reference voltage, the amount of the frequency division of theemultivibrators and 6, and the number oi poles' i In the example shown the more turns of 1500 revolutions per minuteI'The -speed -"is reduced by gear train I I so that radiating element I0 rotates at 1200 revolutions per minute. Since the output of the transmitter is one pulse per cycle of-reference voltage or- 800 pulsesper'second, then'umber of pulses-perrotation of the radiating element-= isfixed at 4:0 pulses per revolution. While there has been described whatis at present consideredthepreferred embodiment ofv the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein --without departing from theinvention, and it is, therefore, aimed in the ppendedclaimsto cover all such changes and modifications as fall within the true spirit and scope ofthe invention. r 1

1. Arr-electrical circuit for synchronizing the pulse repetition frequency of-a transmitter-means otor ila at least one Wien bridge filter.

producing pulses of radio frequency energy for radiation by said radiating element, the pulse repetition frequency of said transmitting means being synchronized by said input reference voltage, means for subdividing the frequency of said input reference voltage, said means comprising two multivibrators and a Wien bridge filter connected: in series, and,an--inverter means for supplyingsaid; subdivided reference voltage to said synchronous motor.

.2. An electrical system for synchronizing the pulse repetition frequency of a transmitter with theQrotation of a radiating means comprising a source of alternating reference voltage; means for subdividingrtheirequency of said reference voltagel-ra: radiating. means; an electrical means for driving 'saidr'rradiating means; means for applying said subdivided reference voltage to said driving means for controlling the movement of said radiating means in synchronism with said subdivided reference voltage, said applying means also being the source ofv energy. forsaidldriying means; and transmitter means connected to said source of referenceovoltagefor generating radio;

frequency pulses in synchronism with said reference voltage and feedingnit. to said radiating 3. A system in accordance with claim 2 wherein said frequency subdividing means comprises a. plurality of multivibrators connected in series an JOHNK, McKsN RY. RE ERENCESEITED The following referenoes are of record in the file of this patent:v o,

UNITEDSTATES PATENTS Number Name Q 'Date 1,436,676 Peterson Nov. '28,; 1922 1,928,793 Poole Oct. 3, 19 33 2,166,688 Kell' July 18, 1939 2,236,532

Gibbs Apr. 1, 1941' 

